Apparatus for gaging and classifying sheets



April 16, 1957 w. E. coLEMAN APPARATUS Foa @AGING AND CLASSIFYING SHEETS Filed July 2a, 195s APPARATUS FR GA-iig1 AND CLASSG William E. Coleman, Pittsburgh, Pa., assigner to United States Steel Corporation, a corporation of New .ersey Application .luiy 28, 1953, Serial No. 370,769

4 Claims. (Cl. 209-82) This invention relates to apparatus for gaging and classifying sheets such as tin plate. The most common practice in gaging and classifying tin plate is to gage the plate in strip form rather than in sheet form. For such a purpose gages such as shown in the patents to Clapp No. 2,488,269, dated November l5, 1949, and Bernstein No. 2,518,115, dated August 8, 1950, are commonly used. However, these gages presenta disadvantage when gaging sheets because there is no means for interrupting the operation of the gage by the sheets. Apparatus has been provided for gaging and classifying sheets such as shown in the patent to Odquist No. 2,3l2,357, dated March 2, 1943. However, the apparatus to Odquist presents a disadvantage because of its slow rate of gaging and classifying and because there is no means for desensitizing the gage when there is no sheet therein.

It is an object of my invention to provide apparatus which will automatically gage and classify sheet material.

This and other objects will be more apparent after referring to the following specification and attached drawings, in which:

The single ligure is a schematic showing of the classifying apparatus and wiring diagram therefor.

Referring more particularly to the drawing, the reference numeral 2 indicates a motor driven conveyor over which sheets S, to be gaged and classified, pass in closely spaced relationship. The conveyor 2 is preferably a belt conveyor having a pair of spaced apart belts for supporting the sheets. The sheets S are fed from a pile 4 to the conveyor 2 and pass successively over a deector gate 6, a motor driven conveyor 8, a deector gate l and a third motor driven conveyor 12 into prime pile i4. The gates 6 and l0 are operated by means of solenoids 16 and 18, respectively. A motor driven conveyor 2) is located on the discharge side of conveyor 2 and feeds oi-gage sheets into the off-gage pile 22. A sirrilar conveyor 24 is located at the discharge end of conveyor 8 and directs off-gage sheets to the oli-gage pile 26. A radioactive source 28 is located beneath the path of travel of the lsheets S on the conveyor 2 and a pick-up head 30 for picking up the signal for the radioactive source 28 is arranged above the path of travel of the sheets S. The radioactive source 28 is connected to a gage control 32 which in turn is connected to a preamplifier 34. The gage head 30 is also connected to the preamplifier 34. An amplifier 36 and phase detector 38 are connected in series with the preamplilier 34. The parts 28, 38, 32, 34, 36 and 3S are parts of the standard gage shown in the Clapp and Bernstein patents discussed above. However, the gages disclosed in the patents depend upon averaging the actual measurements of the gage in a long length of strip being gaged. For example, at line speeds in the neighborhood of 1000 ft./min. approximately 30 feet of the strip is averaged. Such apparatus is not suitable for gaging sheets. A resistor 40 and condenser 42 are connected in series with phase detector 38. Normally closed contacts 44 and a meter 46 are connected in parallel With the condenser 42. A relay coil 48 controls the operation of contacts 44. A light source 50 is located above the sheets S on the conveyor 2 a distance less than the length of a sheet from the pick up head 30. A photosensitive device 52 is mounted below the sheets S directly below the light source 50. A pulse lengthener 54 is connected to the photosensitive device 52 and the relay coil 48. The out-put of the gage circuit is connected to a control circuit 56 through a condenser 58 and a resistor 60. As shown, the control circuit 56 consists of an amplifier 62, a phase inverter 64, a potentiometer 66, a pulse lengthener 68 and a potentiometer 70 and pulse lengthener 72 connected in parallel with the potentiometer 66. The pulse lengtheners 68 and 72 `are preferably of the type disclosed in my copending application, Serial No. 273,697, filed February 27, 1952, now Patent No. 2,655,620. The outputs of pulse lengtheners 68 and 72 are connected to solenoids 74 and 76 of a proportional timer 78 which is mechanically connected to be driven by the conveyor 2. This proportional timer is preferably of the type described in the patent to Ladrach Patent No. 2,217,342 and is equipped with contact mechanism that energizes solenoids 16 and 18.

The operation of the device is as follows.

When there is no sheet in the gage the contact 44 wiil be closed so that the capacitor or condenser 42 will be shorted out and no voltage will appear yacross it. When a sheet enters the gage there will be no voltage across the capacitor 42 until the leading end of tbe sheet intercepts the light from light source 50. When this occurs the electronic pulse lengthener 54 is actuated by photocell 52 thus energizing relay coil 48 for a iixed period of time which is set to de-cnergize the relay before the trailing end of the sheet passes the beta-ray beam generated by the ray source 28. Energization of coil 48 opens contacts 44 and permits the signal from the preampliiier 34 to pass through amplifier 36, phase detector 38, resistor 40, condenser 42 and meter 46. If the sheet is on-gage the signal will be zero because the initial adjustment of the gage control 32 balances out the on-gage signal entering preamplifier 34. Thus no voltage will build up across the capacitor 42. If the sheet is too thick, a voltage of positive polarity will appear at the output of phase detector 38 and start charging capacitor 42 through resistor 40. The capacitor will charge for a short period of time, such as 0.1 second, after which the relay coil 48 is `deenergized and the contacts 44 closed. Closing of contacts 44 quickly discharges capacitor 42 and produces a voltage pulse across capacitor 58 and resistor 60. The magnitude of the Voltage pulse is a measure of the amplitude of the deviation in gage and its polarity is an indication of the direction of the deviation. The same pulse appears across meter 46 and indicates the magnitude and direction ofY deviation in gage. Shortingthe capacitor 42 between each measurement vinsures that each sheet will be measured individually .and will not be inuenced by the measurement on .the preceding sheet. The voltage that appears across capacitor 42 has a saw-tooth wave form, that is, it rises slowly and drops very rapidly when the short is applied by contact 44. 'Ihis wave form is differentiated by capacitor 58 and resistor 60 and gives a voltage pulse across resistor 60 that is very sharp and has an amplitude and polarity determined by the deviation from normal gage. This pulse is amplified by amplifier 62 and transmitted through phase inverter 64 to potentiometer 66 and also potentiometer 70. Positive pulses from ampliiier 62 passing through potentiometer 79, if of sufficient amplitude, will trigger pulse lengthener 72 which in turn will provide an out-put pulse of suliicient amplitude and duration to operate solenoid 76. Energization of solenoid 76 will cause the proportional timer 78 to energize solenoid 16 causing it to move the gate 6 to deect the sheet into the off-gage pile 22. If the sheet is l tion'ofsolenoidJM will causeproportionaljtimer'to energize'solenoid 18-and-divert the sheet totheoigage Aplie 26. The potentiometers` and70 willonly operate their respective pulse lengtheners when apositivepulse isapplied-thereto so that there is no danger otboth Ygates' and 1i) opening at the same time. If desired, only'a single oil-gage pile maybe used in'which case pulse lengtlieners 68 and '72 Will'be arranged so that either pulse lengthener will operate the one deflector gate. -`Potentiometers 66 and 79 may be set -mauually so-thata signal of any desired amplitude Iwilltrigger'the 'classifyingrpulse lengtheners. In other words theseV two potentiometers'determine how much oft-gage a sheetmustbeihefore it is rejected. Additional potentiometers may beadded and set at ditlerent values to control other 'similarclassifying*circuits so that by adding additional pilesthe 'sheetscould Abe separated into as many gages as desired.

While one embodiment-oilily invention has been sho-wn and described it-will lhe apparent that other adaptations and modiications may bevmade Without departing from the scope ofthe following claims.

I Claim:

1. Apparatus for VvautomaticallyY gaging sheets traveling successively in a given path of travelcomprising a radioactive source located on vone side of the path of travel of said sheets, means onthe opposite side of the path of travel of said sheets forpickingup'thesignal'from said radioactive source, a circuit connected to said last named means including a phase detector, resistor and condenser connected in series, normally closed contacts Yconnected in parallel with saidfcondenser, alight source located less than the length of one sheet from said radioactivesource on one side of the path of travel of'said sheets, a photosensitive device located `on the-other side of the path of travel of said sheets opposite said light source, a circuit including said photosensitive device and means'for operiing said normally closed'contacts when a sheet interrupts the light from said light source, and .a meter connected in parallel with said condenser for measuring the gage of said sheets.

2. Apparatus forsautomatically gaging sheets traveling successively in a-given path of'travel comprising a radioactive'source located onzone` side of therpath of travel of said sheets, means :on the opposite side of the path of travel `of'said'sheetsfor picking up the signal from said radioactive source,'a circuit connected -to said last named means including anamplitier, a phase detector, resistor and condenser connected in series, normally closed contacts connected viirparallel with said condenser, alight source located less than the length of one sheet from said radioactive source ouv-one side of th'e path of travel of said sheets, a photosensitive device located on the other side of lthe path of travelv of said sheets opposite said light sourceya circuit inclu'ding'said Vphotosensitive device, a pulse lengthener and a'relay coil'for opening said normally closed contacts when a sheet interrupts the light from said light source, and a meter connected in parallel with said `condenser for measuring the'gage of said sheets.

3. Apparatus for automatically gaging and classifying sheets comprising a pair of conveyors arranged in tandem over which the sheets pass, a deilector between the conveyors for deilecting selected sheets from their path of travel, a radioactive source located on one side of the path of Vtravel tof said sheets over the lrst fof saidconveyors, means on the opposite side of the path of travel of said sheets over the first of said conveyors for picking up the signal from said radioactive source, a circuit connected to said last namedY means including a phase detector, resistor and condenser connected in series,V normally closed contacts connected in parallel with said condenser, a light source located less than the length ofone sheet from said radioactive source on one side of the path of travel of said sheets, la photosensitive device located on the other side of the pat-h of traveler said sheets oppositersaid'light source, a circuit including said photosensitive` device/and means for yopening said normally closed contacts whena sheet interrupts the light from ysaid light source, means for operating said deector, a control circuit operable by the output of said first circuitfor operating said'deector operating means when a sheet is oi gage.

4. Apparatus for automatically gaging and classifying sheets comprising three conveyors arranged in tandem over which the sheets pass, atirst deflector between the rst two conveyors vfor deflecti'ng selected sheets from their path of travel, a second Vdeilector between the second and third conveyors for deecting selected sheets from their path fof travel, a radioactive source located on one side of thepath of travel of said sheets Yover the first of said conveyors, means on the opposite side of the path of travel of said sheets over theV tirst of said conveyors for picking up the signal from said radioactive source, a circuit connected to said last named means including an amplifier, phase detector, resistor and condenser connected in series, normally closed contacts connected in parallel with said condenser, alight source located less than the length of one sheet from said radioactive source on one side of the path of travel of said sheets, a photosensitive device -located on the other side of the path of travel of said sheets opposite said light source, a circuit including said photosensitive device and a relay coil for opening said normally closed contacts when `a sheet interrupts the light from said light source, ,separate means for perating each of said deflectors, a control vcircuit operable by the output ofsaid rst circuitY for operating one of the deilector operating means when a sheet is oi gage in one direction and acontrol circuit operable by the output .oi said first circuit for operating the other deilector operating means when a sheet is oli gage in the other direction.

References Cited in the file of thispatent UNITED STATES PATENTS 2,395,482 Hurley Feb. 26, 1946 2,570,288 Todd Oct. 9, 1951 2,679,317 Roop May 25,1954 2,742,150 Rendel Apr. 17, 1956 

